Electrocatalysis最新文献

The efficiency of the anticorrosive ability of benzoic acid (M1), salicylic acid (M2), gallic acid (M3), and phthalic acid (M4) was evaluated using AISI 316 stainless steel (SS) and 0.5 M HCl via the potentiodynamic polarisation method, electrochemical impedance spectroscopy, contact angle, and scanning electron microscopy analysis. It was found that while inhibition efficiency increased with increasing concentrations, M4 was a better inhibitor than M1, M2, and M3 under the same concentrations when temperature was increased. The results from different analytic techniques were consistent. The tested inhibitors were adsorbed on the SS surface following the Langmuir isotherm. The difference in anticorrosive effectiveness may be due to the inhibitors’ number of –COOH and –OH groups. Quantum chemical parameters were calculated by the density functional theory at the level of the B3LYP theory with bases 6-31G(d,p) and 6–31 + + G(2d,p). Various parameters were calculated, including the highest occupied (E_HOMO) and lowest unoccupied (E_LUMO) molecular orbital energies, electronegativity (χ), energy gap (∆E), chemical hardness (η), softness (σ), electronegativity (χ), electrophilicity (ω), and nucleophilicity (ε), to show the anticorrosive properties of M1, M2, M3, and M4.

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In this study, a simple and low-cost green chemistry process was employed to synthesize mixed Bixbyite (Mn₂O₃) and Hausmannite (Mn₃O₄) nanopowder. It consists of a wet chemistry method using Olive Leaf Extract (OLE), whom bioactive constituting compounds, including polyphenols, act as complexing and reducing agents, promoting oxide nucleation, and followed by moderate annealing at 500 °C, allowing co-crystal growth. The nanopowder was then deposited on a Conradty Nürnberg Noris D-type carbon (CND) substrate, forming a homogeneous well-adhered layer, and the electrochemical performance of the resulting electrode was evaluated toward supercapacitor application. Galvanostatic charge/discharge (GCD) and cyclic voltammetry (CV) analyses revealed outstanding capacitive performance. Specifically, high specific capacitance values of 552.4 F g^− 1 (from CV at a scan rate of 5 mV s^− 1) and 512.8 F g^− 1 (from GCD at a current density of 4 A g^− 1) were measured. A good rate capability and stable cycling behavior with 91.84% retention were also observed. These results establish a clear correlation between the enhanced supercapacitive properties of the engineered electrode and its superior interfacial characteristics. Python-based multiphysics numerical modeling validated these issues, providing deeper insights onto their hybrid charge storage mechanism.

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A combined numerical simulation and experimental study of Mn2O3-Mn3O4/CND supercapacitor electrodes

The rapid and selective detection of 2,4,6-trinitrotoluene (TNT) is critical for environmental monitoring and national security. In this study, a novel electrochemical sensor based on a self-assembled nanocomposite comprising zero-valent iron (Fe), graphene nanoplatelets (GNPs), and tetra(4-carboxyphenyl) porphyrin (TCPP) was developed for TNT detection. The Fe/GNPs@TCPP nanocomposite exhibited a porous, fibrous structure with enhanced conductivity, high surface area, and strong affinity for nitroaromatic compounds. Structural and chemical characterizations confirmed the successful integration of the components. Electrochemical analysis demonstrated excellent sensitivity and selectivity for TNT, with a clear and reproducible response in both cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The optimized composite displayed a low detection limit of 0.104 µM and a wide linear range, outperforming conventional materials. Its performance remained stable under various pH conditions and scan rates, demonstrating proton-coupled electron transfer behavior. The synergistic interaction of Fe, GNPs, and TCPP enhances both electron transfer and analyte recognition, making this nanocomposite a promising candidate for field-deployable TNT sensors.

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Platinum supported on reduced graphene oxide doped with sulfur and nitrogen (Pt/NSC) is presented in this study as an efficient electrocatalyst for energy-related reduction reactions, namely hydrogen evolution (HER) and oxygen reduction (ORR). A thermally stable poly bis(thiophen-2-yl methylidene) hydrazine serves as a single-source precursor for dual heteroatom doping with nitrogen and sulfur. The Pt/NSC catalyst exhibits an overpotential of only 19 mV vs. RHE at a current density of 10 mA cm⁻², outperforming commercial 20% Pt/C (42 mV). Its lower activation barrier, revealed by Tafel slope analysis, further confirms enhanced kinetics. RDE linear sweep voltammetry indicates a favorable four-electron pathway, suitable for fuel cell applications. Accelerated stress testing confirms excellent durability for ORR. These results demonstrate that heteroatom doping and the least Pt content significantly improve ORR/HER electrocatalytic activity. Material and electrochemical characterization validate the design and efficiency of Pt/NSC, supporting its potential as a cost-effective electrocatalyst.

The design and development of highly efficient and affordable oxygen evolution reaction (OER) electrocatalysts are crucial for linking water splitting to clean, renewable energy storage. In this study, nanostructured samarium-doped lanthanum nickelate (La₂NiO₄) perovskite oxides were synthesized via the citric acid-based combustion method and evaluated for their OER performance in alkaline media. Among the prepared samples, La₁.₈Sm₀.₂NiO₄ (LS_0.2NO) exhibited distinct structural features and intrinsic catalytic properties that led to remarkable OER activity. More importantly, LS_0.2NO demonstrated exceptional stability and achieved a current density of 10 mA·cm⁻² at a low overpotential of 350 mV in alkaline water electrolysis. The optimized catalyst showed a high electrochemical surface area (86.2 cm²), a Tafel slope of 75 mV/dec, and a turnover frequency (TOF) of 0.05 s⁻¹ at 10 mA·cm⁻². This performance highlights the potential of Sm-doped La₂NiO₄ as a cost-effective alternative to noble metal-based OER electrocatalysts.

In the field of energy storage, transition metal oxide thin films have become an exceptional candidate for electrode fabrication in recent times. In this study, we attempt to figure out the influence of annealing temperature on the structure and surface morphology, and also the impact on electrolyte ion transfer kinetics through porous NiCo₂O₄ (NCO) electrodes. NCO thin films have been efficaciously synthesized on conductive stainless steel (SS-304) substrate by using the potentiostatic electrodeposition technique followed by annealing at different temperatures (350℃, 400℃, and 450℃). The galvanostatic charge-discharge (GCD) plateaus reveal NCO-350 electrode exhibits a maximum specific capacitance of 896 F/g at 1 A/g. Electrochemical impedance spectroscopy (EIS) results suggest minimal diffusion resistance of the electrolyte ions confirming good conductive nature of the samples. After 3000 cyclic voltammetry (CV) cycles, the NCO-450 electrode possesses the highest capacitance retention value of 94.9% among all three electrodes. The overall electrochemical performance highlights the potential of NiCo₂O₄ thin films as efficient electrode materials for high-performance supercapacitors.

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A Sn/ZnO₂@Ti₄O₇ anode was prepared using a combination of hydrothermal synthesis and discharge plasma sintering methods for the electrochemical degradation of perfluorooctanoic acid (PFOA). The introduction of Sn/ZnO₂ significantly increased the electrochemical active surface area (ECSA) and the oxygen evolution potential (OEP) of Ti₄O₇. A 97.6% degradation rate of PFOA can be achieved using a Sn/ZnO₂@Ti₄O₇ anode, at a current density of 40 mA/cm², with the initial PFOA concentration of 10 mg/L, at a pH value of 5.69, and within 120 min. Radical quenching experiments indicated that direct oxidation was the main mechanism for PFOA degradation, contributing 82.5%. The degradation efficiencies of PFOA remained above 88% in Dongjiang and Zhujiang rivers (DJR and ZJR) matrixes, confirming the system’s resistance to complex matrix. The total organic carbon (TOC) removal ratio was 56.8%, and the defluorination ratio was 48% after electrolysis of 6 h. After 36 cycles of degradation, the degradation rate was 95.6%. The toxicity assessments indicated that the degradation intermediates were significantly less toxic than the parent PFOA.

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The quick decline of fossil fuels caused by high consumption levels has boosted the creation of sustainable energy conversion systems, resulting in a growing energy crisis. The ongoing energy requirement drives the exploration of innovative options for water splitting. It is critical to develop an exceptionally efficient electrocatalyst that can enhance the sluggish oxygen evolution reaction (OER). BiFeO₃ and Sm-doped BiFeO₃ were manufactured via sol–gel technique and investigated as a catalyst for OER in a 1.00 M KOH. The morphology and crystalline phases were resolved by utilizing a different analytical technique. The Sm-doped BiFeO₃ displayed efficient OER performance having overpotential (η = 186 mV) at 10 mA /cm² and Tafel value (32 mV/dec) and solution resistance (R_s) of 0.83 Ω. In addition, the electrocatalytic efficiency of Sm-doped BiFeO₃ catalyst for OER exhibits exceptional sustainability for 40 h and an increased electrochemically active surface area (ECSA) of 897.5 cm². The better performance of the Sm-doped BiFeO₃ catalyst may be linked to several factors, including its distinctive interrelated morphology, strong synergistic interactions between Sm, Bi and Fe and effective OH⁻ ions adsorption. The results indicate that Sm-doped BiFeO₃ has potential as an electrocatalyst in practical applications.

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The electrochemical CO₂ reduction to produce valuable chemicals is a viable approach for mitigating carbon emissions. In this study, a high-entropy oxides (HEOs)-based electrocatalyst comprising the oxide of transition metals (M = Co, Fe, Zn, Ni, and Cu; termed CFZNC) anchored on activated-carbon powder (ACP) is synthesized by the polymerization of phenol and formaldehyde in situ dispersed with the respective metal salts, followed by ball milling and thermal treatment (carbonization and steam activation) of the synthesized polymeric beads. The electrochemical characterization tests of the prepared CFZNC-HEO/ACP electrocatalyst confirm a high current density of 10 mA.cm⁻² at a low applied potential of − 0.37 V vs. RHE. The electrochemical CO₂ reduction tests reveal a formate (HCOO⁻) Faradaic efficiency of 98 ± 4.9% and a cathodic energy efficiency of 86 ± 4.3% at − 0.4 V, thus highlighting an efficient energy utilization of the material and selectivity toward formate production. Notably, the comparative tests reveal CFZNC-HEO/ACP outperforming its high-entropy alloy (HEA) counterpart, viz. CFZNC-HEA/ACP-based electrocatalyst, thus obviating the need for the high-temperature hydrogen-reduction step required to transform metal oxides to metal alloy. The enhanced performance is attributed to the synergistic effect of the multiple metal oxides in the high-entropy formation and the highly porous and conductive carbon substrate. These findings demonstrate the promise of high-entropy metal-oxide-based electrocatalyst in advancing efficient and sustainable CO₂ reduction technologies.

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